Methods are being devised and tested to improve the detectability of trace organic compounds using mass spectrometry. The development of new derivatization reagents and methods to impart improved electron capture properties and ionizability for negative ionization mass spectrometric detection has been continued. A variety of derivatives are being tested for quantitative analysis of anandamide (arachidonylethanolamide), an endogenous cannabinoid agonist found in mammalian brain and peripheral tissues, for kynurenine and kynurenic acid, and for the amino acids nitrotyrosine and tyrosine as biomarkers of peroxynitrite from nitric oxide released in tissues. Liquid-chromatography - electrospray mass spectrometry is being investigated for trace detection analyses of lipids related to anandamide and products of the kynurenine pathway metabolism of tryptophan, and for oxidized nucleosides. Liquid chromatography - matrix assisted laser desorption mass spectrometry is being tested as a means of analyzing NAD and NADP as products of tryptophan metabolism. (Formerly LCS)